In order to study the groundwater environment in the Longkou plain,48 groups of water samples are collected,consisting of 7 groups of surface water samples and 41 groups of groundwater samples.The quality of groundwat...In order to study the groundwater environment in the Longkou plain,48 groups of water samples are collected,consisting of 7 groups of surface water samples and 41 groups of groundwater samples.The quality of groundwater in the Longkou Plain is poor,with class V water quality accounting for more than 90%,and no class I,II water quality,sporadic distribution of Class III and IV water quality.The influencing factors of water quality are mainly inorganic indicators such as nitrate,total hardness,chloride,salinity and sulfate,the detection rate of heavy metals is low.Nitrate is the main pollution index in this area,and the increase of nitrate content is closely related to the construction of underground reservoir.Based on the characteristics of groundwater pollution in the Longkou Plain,the in-situ chemical remediation of groundwater pollution is proposed.展开更多
Non aqueous phase liquids (NAPLs) pollution are worldwide problems at present. NAPLs which enter the underground through spills or leaks may cause long lasting soil and groundwater contamination problems. Groundwater ...Non aqueous phase liquids (NAPLs) pollution are worldwide problems at present. NAPLs which enter the underground through spills or leaks may cause long lasting soil and groundwater contamination problems. Groundwater can be contaminated by non aqueous phase contaminants that are less dense (LNAPL) or denser (DNAPL) than water. The movement of both types of NAPLs will be influenced by the hydrogeological conditions, such as groundwater level, hydraulic conductivity, and porosity etc., however, LNAPL pollutants tend to concentrate at the water table while DNAPL may migrate further down. Understanding the underground migration mechanisms of NAPLs is of primary importance in pollution prediction and site remediation. Several laboratory simulations for NAPLs’ underground movements in porous media have been done in the past (A.S.Abdul et al., 1988, 1989; C.Tang et al., 1995). In this paper, we try to use STOMP (Subsurface Transport Over Multiple Phases) code to simulate the underground migration of NAPLs. The main purposes are: (1). to understand NAPLs’ underground migration mechanisms; (2). to analyze the sensitivities of model parameters, such as hydraulic conductivity, porosity, etc., and to know what are the most sensitive and important parameters in the model application; and (3). to study NAPLs movements in different hydrogeological conditions. The simulations include: Through the computer simulation, we have found that hydraulic conductivity and porosity are very sensitive in the model simulation, small changes of these parameters will cause big difference of the results, therefore, it is essential to accurately determine these parameters for high quality model simulation; The movements of NAPLs in different geological formation are quite different, two different geological media ( clayey sand and sand ) have been chosen in this paper to simulate NAPLs movement with different combinations ( i.e., moving from clayey sand to sand, and from sand to clayey sand ), the results have been analyzed and discussed; Finally, the influence of groundwater level variation to NAPLs (LNAPL and DNAPL) movement has been simulated by using pumping and injecting wells in the model. The results are compared with laboratory simulations conducted by C.Tang et al.. These results may helpful to understand the behavior of NAPLs during the remediation, such as pumping and treat, and air sparging. It is also important to the design of the remediation plans.展开更多
为高精度地开展地下水污染溯源辨识,在对污染源参数进行敏感性分析的基础上,研究应用两阶段马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)算法辨识确定污染源参数;同时,探索应用多层感知机(Multi-layer Perceptron,MLP)方法构建...为高精度地开展地下水污染溯源辨识,在对污染源参数进行敏感性分析的基础上,研究应用两阶段马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)算法辨识确定污染源参数;同时,探索应用多层感知机(Multi-layer Perceptron,MLP)方法构建地下水污染运移数值模型的代理模型,用以提高地下水污染溯源辨识的效率。为验证上述方法的有效性和可行性,开展了两个数值算例研究。结果表明:采用MLP方法构建的代理模型对地下水污染运移数值模型的逼近精度高,不仅能够有效提升地下水污染溯源辨识效率,还能保持良好的计算精度;所提出的耦合敏感性分析与两阶段MCMC算法能够显著提升低敏感性污染源参数的辨识精度。展开更多
文摘In order to study the groundwater environment in the Longkou plain,48 groups of water samples are collected,consisting of 7 groups of surface water samples and 41 groups of groundwater samples.The quality of groundwater in the Longkou Plain is poor,with class V water quality accounting for more than 90%,and no class I,II water quality,sporadic distribution of Class III and IV water quality.The influencing factors of water quality are mainly inorganic indicators such as nitrate,total hardness,chloride,salinity and sulfate,the detection rate of heavy metals is low.Nitrate is the main pollution index in this area,and the increase of nitrate content is closely related to the construction of underground reservoir.Based on the characteristics of groundwater pollution in the Longkou Plain,the in-situ chemical remediation of groundwater pollution is proposed.
文摘Non aqueous phase liquids (NAPLs) pollution are worldwide problems at present. NAPLs which enter the underground through spills or leaks may cause long lasting soil and groundwater contamination problems. Groundwater can be contaminated by non aqueous phase contaminants that are less dense (LNAPL) or denser (DNAPL) than water. The movement of both types of NAPLs will be influenced by the hydrogeological conditions, such as groundwater level, hydraulic conductivity, and porosity etc., however, LNAPL pollutants tend to concentrate at the water table while DNAPL may migrate further down. Understanding the underground migration mechanisms of NAPLs is of primary importance in pollution prediction and site remediation. Several laboratory simulations for NAPLs’ underground movements in porous media have been done in the past (A.S.Abdul et al., 1988, 1989; C.Tang et al., 1995). In this paper, we try to use STOMP (Subsurface Transport Over Multiple Phases) code to simulate the underground migration of NAPLs. The main purposes are: (1). to understand NAPLs’ underground migration mechanisms; (2). to analyze the sensitivities of model parameters, such as hydraulic conductivity, porosity, etc., and to know what are the most sensitive and important parameters in the model application; and (3). to study NAPLs movements in different hydrogeological conditions. The simulations include: Through the computer simulation, we have found that hydraulic conductivity and porosity are very sensitive in the model simulation, small changes of these parameters will cause big difference of the results, therefore, it is essential to accurately determine these parameters for high quality model simulation; The movements of NAPLs in different geological formation are quite different, two different geological media ( clayey sand and sand ) have been chosen in this paper to simulate NAPLs movement with different combinations ( i.e., moving from clayey sand to sand, and from sand to clayey sand ), the results have been analyzed and discussed; Finally, the influence of groundwater level variation to NAPLs (LNAPL and DNAPL) movement has been simulated by using pumping and injecting wells in the model. The results are compared with laboratory simulations conducted by C.Tang et al.. These results may helpful to understand the behavior of NAPLs during the remediation, such as pumping and treat, and air sparging. It is also important to the design of the remediation plans.
文摘为高精度地开展地下水污染溯源辨识,在对污染源参数进行敏感性分析的基础上,研究应用两阶段马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)算法辨识确定污染源参数;同时,探索应用多层感知机(Multi-layer Perceptron,MLP)方法构建地下水污染运移数值模型的代理模型,用以提高地下水污染溯源辨识的效率。为验证上述方法的有效性和可行性,开展了两个数值算例研究。结果表明:采用MLP方法构建的代理模型对地下水污染运移数值模型的逼近精度高,不仅能够有效提升地下水污染溯源辨识效率,还能保持良好的计算精度;所提出的耦合敏感性分析与两阶段MCMC算法能够显著提升低敏感性污染源参数的辨识精度。
